Automatic electric heating iron



Jan. 2, 1940.

G. c. HEINRICH 2,185,197

AUTOMATIC ELECTRIC HEATING IRON Filed Oct. 21, 193'! 2 Sheets-sheaf, l

INVENTOR fiearge 6'. Heinriah A TTORNE KS Jan. 2, 1940; r G Q CH 2,185,197

AUTOMATIC ELECTRIC HEATING IRON Filed Oct. 21. 193? 2 Sheets-Sheet l N V E NTP R Gearge 6'. Hannah Wom Patented J n. 2, 1940 3,185,197 AUTOBIATIO EIEC'IR IO HEATING IRON George 0. Heinrich, Meriden, m, assignmto Manning. Bowman I: 00., Madden, Coma, a corporation of Delaware Application October 21, 1937, Serial No. 110,236

12 Claim.

This invention relates to automatic electric heating irons.

One object of the invention is an automatic iron in which the initial overshoot of temperature,

when the iron is initially connected in circuit, is very substantially reduced as compared with conventional irons.

A further object of the invention is an automatic iron wherein the amplitude of the temperature curve resulting from the operation of the thermostat is reduced as compared with the amplitude of the curve of conventional irons.

A further object of the invention is an automatic iron which is more sensitive to temperature changes and in which better and more eflicient temperature regulation is obtained than with conventional irons.

A further object of the invention is an automatic iron embodying a novel regulating mechanism.

A further object of the invention is an automatic iron characterized by the simplicity of its structure'and its regulating mechanism.

Further objects of the invention will hereinafter appear. I

For a better understanding of the invention reference may be had to the accompanying drawings forming a part of this application wherein:

Fig. 1 is a part elevational and sectional view of an iron embodying the invention;

Fig. 2 is the circuit diagram;

Fig. 3 is a perspective exploded view showing parts of the sole plate of Fig. 1 in the process of assembly; and

Fig. 4 is a graph indicating the reduced initial overshoot and the reduced amplitude of the temperature curve.

Referring to .the drawings the invention is illustrated as embodied in an iron having a sole a heel rest 4, and a thermostatic regulating unit 5, the sole plate being tapered in thickness from the nose to the rear and being thicker at the nose.

5 The invention is particularly applicable to automatic irons wherein a resistance unit 8 is embedded in a body 01' cementitious material I carried by the sole plate base. The sole plate casting is provided with an integral metallic flange 8 near the border or peripheral edge thereof for retaining in place the cementitious body I which forms the upper surface of the sole plate base and which has embedded therein the resistance unit 8. The upper surface of the cementitious body 1 45 is on a level with the upper edge of the flange I.

plate I, an upper casing or cover 2, a handle 3.

The cementitious body covers the whole of the upper surface of the sole plate within the confines of the retaining flange ii, except that a narrow elongated chamber A is formed centrally thereof for the reception of the thermostatic element 20 of a regulating unit 5 and the sole plate casting is provided at points adjacent this narrow elongated chamber A with integrally formed upwardly extending projections or parts It and It for fastening the casing or upper part of the iron to the sole plate. These supporting and fastening parts It and it are, in the particular embodiment shown, of the same height as the outer retaining flange 8 and the upper surfaces thereof are on a level with the upper surface of the cementiticus body. At its rear end the narrow elongated chamber A for accommodating the thermostatic element 20 is slightly enlarged laterally into a part B, the latter accommodating a U bracket 28 having legs 30 and attaching feet 3|.

In the particular embodiment of Figs. 1 and 4 the slightly laterally enlarged part B of the elongated chamber A is defined by a flange 9 formed integrally with the sole plate casting and the projecting fastening parts it and of the same height as the projections It, while the fastening part It is formed with a flat side 9' which defines the other end of the narrow elongated chamber A. The chamber A is slightly wider than the thermostatic element III in order to facilitate the mounting of the element therewithin, but the thermostatic element is thus closely and directly exposed to the cement body I having the heating units I embedded therein. This element 20 is also fastened flat against the bottom of the chamber A, namely, directly in contact with the iron of the sole plate. that is, the anchored end of the member 2. is thus fastened, as for example by the screws' il'. The thermostatic element 20 is thus rendered very sensitive to the temperature conditions of the sole plate I and also to the heat radiations from the cement embedded heater element 8, to both of which the element is directly exposed. When the cementitious body I is of a character to relieve or give of! small particles of sand, grit, dust, and the like which may int'erfere with the adjustment and operation of the thermostatic regulating unit it is preferred that the sides of the narrow elongated chamber A be also provided with thin separating partitions so as to have the whole chamber partitioned off on all sides, but such side partitions should be thin enough and preferably of a character not to impede or hinder the transmission of radiant heat rays from the cement embedded resistance element 6 to the thermostatic element 2!. I have indicated such thin side partitions or walls at III which may be of glass or mica, preferably mica. These mica windows or partitions do not need to become heated up before they transmit the radiant heat energy along to the thermostatic element, as is the case with cast iron and other metallic partitions, withthe result that the thermostatic element responds very quickly to the heat generated by the unit. These thin side partitions or walls I 0 may be supported and fastened in position in any suitable manner.

As indicated above, the thermostatic element 20 extends substantially throughout .the length of the narrow chamber A and at one end is fastened fiat against the iron of the sole plate by the screw bolts 2| in the part B of the chamber A. The free end of the element 20, which is a bi-metallic element, carries on the end thereof a push actuating button or pin 2|, this button or pin 2| having a conical head 2i disposed in a conical recess or depression formed in the base plate and being insulated from the thermostatic element 20 an fastened thereto in any suitable manner.

The thermostatic element regulates the temperature by opening and permitting the closure of the circuit at-the contacts 25. One of these contacts is carried by a spring finger 26 and the other by a spring finger 21, both preferably of stainless steel, the two fingers 2i and 2'! being fastened respectively to the upper and lower sides of a U bracket 2| by means of the screws 29, the U bracket comprising legs 20 which extend down into the. cross part of the housed chamber and are provided with feet ii for fastening to the bottom of the chamber. For this P pose the feet ii are provided with openings or slots for the reception of fastening screws 32. The spring finger 26 carries at its outer end an adjustable actuatingscrew 32 which is eneased by the push button 2| and this finger 26 is spring bimed to cause the screw 22 to approach the actuating button 2| of the thermostatic element. The spring finger 21 has an opposite bias tending to hold the screw 22 from out of engagement with or from approaching the button 2|. By actuating the spring 21 against its bias, the bias spring 26 tends to-bring the actuating screw 32 more closely to the thermostatic element 20, 2| and through the adjustment of screw 32, the adjustments of the tensions of spring fingers 26,21 and the adjustment of spring finger 21 against its bias the temperature to be maintained by the iron may be accurately determined. The adjustment or actuation of the spring 21 against its bias may be effected in any suitable manner, as for example by means of a rotary handle 35 which is operated by the operator and is in operative engagement with a pin "which moves upwardly and downwardly, passing through registering openings in the spring fingers 2B and 21, to engage an'arm'or finger 3'! fastened to and projecting forwardly beneath the finger 21. This projecting finger 21 carries an insulated bearing surface member a which is engaged by the end of the regulating pin II. The temperature to be maintained may be lowered by lowering the pin and raised by elevating the pin 38. Plug terminals for the iron are indicated at II. For the purpose of maintaining a permanently unimpaired contact wlththe spring finger 26 there is shown a layer of silver 26' welded onto the terminal end of this member 26. This is particularly advantageous in irons of the ammo? character illustrated, the temperature and operating conditions of which are severe.

As indicated above, when the sides of the chamber A are provided with thin walls or partitions ID of mica, these thin partitions or walls jection It, 9' forming the end wall of the chamber. The side members l2 have lateral extensicns I4 at either end thereof which extenddownwardly and engage the outer surfaces of the mica walls "I to give support thereto. The parts l2 also have ears l5 formed on their outer ends for resting upon projections It. The parts Hi, It have formed therein screw-threaded openings II for the reception of screw bolts which fasten the upper part of the iron structure to the sole plate and the parts I! and I5 of the mica unit frame are provided with openings l3 and ii for registering with these fastening screw bolts. The sole plate casting is formed with elongated shoulders l8 which are engaged by the mica partitions Ill when the unit is in assembled position. The mica partition unit is preferably positioned and fastened to the cast iron parts l6, l6 prior to pouring the cement l and molding therein the heater elements 6.

In Fig. 4 I have illustrated in full lines 'the general character of the temperature curve obtainable by an iron embodying the invention, while in the dotted lines I have indicated a similar curve obtained from conventional irons of the same general type operating under the same conditions. A comparison of these curves indicates the very substantial reduction of the initial overshoot by the use of the invention as well as the reduction in the amplitude of the variations of temperature during operation.

The windows or partition's Ill, when employed, may be made of any suitable material which does not tend to impede, or does not seriously impede, or which readily permits the passage therethrough of the heat rays, such for example as the infra red rays. sllicious material of the general character of glass and micamay be used, but clear, transparent, single layers of mica are at present the preferred partitions as this material stands up under the high temperature conditions of the iron, is readily mounted and fastened in position and is'found to offer little hindrance, if any, to the passage of the heat rays therethrough.

I claim:

i. In an automatic electric heating iron a sole plate casting having a body of cementitious material on the upper surface thereof, said cementitious body having formed centrally thereof a narrow elongated chamber whose bottom is a part of the sole plate castings temperature regulating unit comprising anelongated thermo static element fastened atone end fiat against For example, any suitable the bottom of said chamber and extending subdirectly exposed to the radiant heat rays from said cementitious body.

2. In an automatic electric heating iron a sole plate casting having a body of cementitious material on the upper surface thereof, said cementitious body having formed centrally thereof a narrow elongated chamber whose bottom is a part of the sole plate casting, a temperature regulating unit comprising an elongated thermostatic element fastened at one end fiat against the bottom of said chamber and extending substantially throughout the length thereof and a. heating element embedded in said body of cementitious material, the sides of said elongated chamber being provided with partitions between the cementitious body and the thermostatic element which offer little resistance to the passage of the heat rays from the cement embedded heating element andithe thermostatic element.

' 3. In an automatic electric heating iron a sole plate casting having a body of cementitious material on the upper surface thereof said cementitious body having formed centrally thereof a narrow elongated chamber whose bottom is a part of the sole plate casting, a temperature regulating unit comprising an elongated thermostatic element fastened at one end flat against the bottom of said chamber and extending substantially throughout the length thereof and a heating element embedded in said body of cementitious material, and thin partitions of a sillcious material being disposed along the sides of said chamber and between the cement embedded heating element and the thermostatic element.

4. In an automatic electric heating iron a sole plate casting having a body of cementitious material on the upper surface thereof, said cementitious body having formed centrally thereof a narrow elongated chamber whose bottom is a part of the sole plate casting, a temperature regulating unit comprising an elongated thermostatic element fastened at one end flat against the bottom of said chamber and extending substantially throughout the length thereof and a heating element embedded in said body of cementitious material, and thin partitions of clear transparent mica being disposed along the sides of the said chamber and between the cement embedded heater element and the thermostatic element.

5. In an automatic electric heating iron, a temperature regulating unit comprising a thermostatic element, a heating element embedded in a cementitious base and disposed about said thermostatic element, said thermotatic element being enclosed in a chamber defined by walls separating the cementitious base and the embedded heating element therein from the thermostatic element, certain sections of said walls being formed of cast iron and certain other sections which are disposed immediately between the movable portion of the thermostatic element and said embedded heating element being formed of a material which offers less resistance to the passage of the heat rays therethrough than the said cast iron wall sections.

6. An automatic iron of the character set forth in claim 5 wherein the second named sections of said wall are formed of mica.

'7. An automatic iron of the character set forth in claim 5 wherein the second named sections of said wall are formed of a silicious material.

8. In an automatic electric heating iron a regulating unit comprising a thermostatic element, a heating element disposed in proximity to said thermostatic element and embedded in a cementitlous base, and a partition disposed between the thermostatic element and the cement embedded heating element formed of a material which permits the passage of heat rays unhindered therethrough.

9. In an automatic electric heating iron, a sole plate having a regulating unit chamber centrally located on the upper side thereof and defined by a wall at least a part of which is formed of a material which permits heat rays to pass therethrough at a more rapid rate than a metallic wall, a cementitious base disposed about said chamber and having molded therein a heating element. a temperature regulating unit comprising a thermostatic element disposed in said chamber with the aforementioned part of the wall disposed immediately between said heating element and said thermostatic element.

10. An iron of the character set forth in claim 9 wherein part of said wall includes a window of a material offering no greater resistance to the passage of heat rays therethrough 'than windows of mica and glass.

11. In an automatic electric heating iron, a temperature regulating unit comprising a thermostatic element, a heating element embodied in a cementitious base and disposed about said thermostatic element, said thermostatic element being enclosed in a chamber defined by walls separating the cementitious base and embedded heating element from the thermostatic element. said walls including windows immediately between the movable part of the thermostatic element and the adjacent part of the cement embedded heating element, said windows being of a material which offers no greater resistance to the passage of heat therethrough than thin walls of mica and glass.

12. In an automatic electric heating iron having an electric heating element embedded in a body of cementitious material disposed on the sole plate casting thereof, said cementitious body having formed centrally thereof a relatively small chamber whose bottom is part of the sole plate casting, an automatic temperature regulating unit comprising a thermostatic element disposed within said chamber and in close heat exchange relation with the sole plate casting and the cementitious body, and said thermostatic element being directly exposed to the radiant heat rays from said cementitious body.

GEORGE C. HEINRICH. ll

CERTIFICATE OF CORRECTION- Patent No. 2,185,197. January 2, 19!;0.

GEORGE G. HEINRICH.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, second column, line 22, for "Figs. 1 and 1;" read Figs. 1 and 5; page 2, second column, line 7, for "Fig. 1;," read Fig. 3; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 12th day of March, A. n. 19u0.'

Henry Van Arsdsle, (Seal) Acting Commissioner of Patents. 

